Digital audio workstations (DAWs) are increasingly popular in the recording studio and post-production environments. Digital audio workstations are used to mix, amplify, control and otherwise affect either the audio portion of a multimedia event or a production, which is solely audio, such as a song or composition. Two important features desirable in any DAW are the DAW's ability to perform audio "tasks" (such as equalization, reverberation, etc.) in a real-time, efficient manner and the ability of the DAW to edit a digital waveform to produce an interesting effect. Recently, digital audio workstations have been implemented using a personal computer, a PC, with specialized sound cards for capture and playback. Because of the processing capability of the PC, a digital waveform can be easily modified prior to playing back the signal. New sounds can be generated that are variations on the original audio. Alternatively, the signal can be "cleaned up" by digital processing techniques to eliminate imperfections in the original sound.
The production of a multimedia program typically involves editing an audio signal to augment the signal in some fashion. The editing of the signal is performed on digital samples generated after an Analog-to-Digital conversion of the analog audio signal. The resulting digital samples may be manipulated using digital signal processing (DSP) techniques to modify the signal in some interesting manner. For example, the playback speed of the stored audio data is changed to produce a new sound that is derived from the original audio. This change alters the duration of the playback sound. A side-effect of this manipulation is a pitch change, that is often referred to as the "chipmunk" effect because of the high pitch that results when voice is played back at high speeds. This pitch change results in an interesting special effect.
Special effects are not limited to only changes in the pitch of the audio, but include other modifications to the signal that produce interesting audio results. An effect typically results from numerically processing a digital representation of the original analog signal by modifying the digital values to produce the special effect. A further example of a special effect that can be generated digitally is a crossfade from one digital waveform to another waveform. The crossfading operation produces a transition between the two signals by phasing in the second waveform from the first waveform in a defined manner. The progression of the crossfade is usually specified by the user and can be adapted to generate a customized sound.
In the entertainment industry, the generation of innovative audio special effects has become increasingly important. Whether it is a sound recording by an artist or an audio/visual work such as a film, a production with unusual visual and audio effects enhances the marketability of the product. Consequently, it is important to discover interesting and novel effects that are efficiently implemented on a workstation such as a digital audio workstation.